Conventionally, apparatuses which can realize a paper-pencil relationship are known, in which a coordinate input apparatus capable of inputting coordinates is placed on the display screen of a display apparatus such as a CRT display, a liquid crystal display (LCD), or a projector so that operator's pointing or handscript by a pointing tool is displayed on the display apparatus.
There are coordinate input apparatuses of a type that uses a transparent input plate, including a resistive film type, an electrostatic type, and an ultrasonic wave type which propagates an ultrasonic wave to a coordinate input surface made of glass or the like. Some coordinate input apparatuses are of an optical type or type which detects a position by radiating a sonic wave into the air. In some coordinate input apparatuses of an electromagnetic induction (electromagnetic transmitting/receiving) type, a mechanism for calculating coordinates is placed behind a display apparatus while a transparent protective plate is placed in front of the display apparatus, thereby constructing an input/output integrated information device.
Such information devices have been used for electronic notepads at first. Along with an increase in the size of display apparatuses, information devices such as a relatively large pen input computer are also becoming popular. Such information devices are combined with wide-screen display apparatuses such as front projectors, rear projectors, or PDPs and used as, e.g., presentation apparatuses or video conference systems. For display apparatuses such as wide-screen liquid crystal displays or PDP displays, image quality improvement and cost reduction are still progressing. As satellite broadcasting and the like are switching to digital broadcasting systems, the specifications and forms of TV sets are also entering a transitory stage.
These wide-screen display apparatuses are replacing, e.g., whiteboards or electronic blackboards used in offices and are used at meetings or briefings by displaying material data that are prepared in personal computers in advance on the wide-screen display apparatuses. In this case, information displayed on the wide-screen display apparatus can be updated by an operator or a participant by directly touching the screen like a whiteboard so that, e.g., the display contents on the display screen can be switched by controlling the personal computer.
In a coordinate input apparatus of this type, particularly, in a coordinate input apparatus of a resistive film type or electrostatic type, however, it is difficult to form a completely transparent input plate, and therefore, the image quality on the display apparatus is low.
In an apparatus of an ultrasonic wave scheme which requires a propagation medium such as a glass plate, the glass surface must be optically processed to prevent, e.g., glare of a fluorescent lamp for indoor use. Hence, if the image quality should be maintained, the cost inevitably largely increases.
In an apparatus of an electromagnetic induction type, an electrode on a matrix is arranged on the lower side of the display screen to transmit/receive an electromagnetic signal to/from a pointing tool. For this reason, when the display apparatus becomes bulky and thick, coordinate calculation is difficult in principle. Additionally, a large-scale coordinate input apparatus for the purpose of conference or presentation is very expensive.
Since a large display system is employed assuming watching by a large audience, a sufficient image view angle and contrast are required. Hence, when such a large display system and coordinate input apparatus are combined, it is important to make it possible to accurately calculate coordinates at a sufficiently low cost and prevent any degradation in image quality of the display apparatus.
When a large input/output integrated system of this type, and briefings assuming many participants or the age of networking are taken into consideration, an arrangement that allows the operator to control an external device such as a personal computer and appropriately display necessary information by directly touching the screen is advantageous for the operator (presenter) from the viewpoint of operability.
In addition, when the operator directly operates information on the screen, listeners as many participants can obtain information such as the point indicated by the operator or the expression or gesture of the operator simultaneously with the information displayed on the screen. This helps better understanding.
However, if the operator directly takes an action to, e.g., indicate a specific position on the display screen of the large display apparatus of this type, information on the screen is hidden by the operator who moves at that time. Especially in a system that employs a display apparatus of a projection type such as a front projector or OHP, the image is greatly distorted, resulting in difficulty to see.
To solve the problem of obstruction on the optical path, the operator may execute an operation like a mouse manipulation (an operation of moving, e.g., a cursor on the basis of not absolute coordinates but relative coordinates) by using appointing tool to move the cursor from the current position to a desired position.
The method of inputting relative coordinates will be described in detail. Assume that, for example, coordinate values (X1,Y1) are detected at given time by operator's operation, and then, the pointing tool is moved, and the coordinate input apparatus detects coordinate values (X2,Y2). The moving amounts are given by (ΔX,ΔY) (ΔX=X2−X1,ΔY=Y2−Y1).
When the cursor is moved on the basis of the moving amounts (ΔX, ΔY), i.e., the moving amounts from the current arbitrary cursor position, the cursor can be moved as the operator's will (the direction and moving distance equal the moving direction and moving amount of the pointing tool). That is, instead of directly locating the pointing tool to a predetermined position on a wide screen, the operator can move the cursor to the predetermined position without changing the position of his/her own.
For the coordinate input apparatus, character input or drawing by directly touching the screen (when the pointing tool is moved, a handscript to the moving position remains as an echo back as if there were a relationship of paper and a pencil) or command generation by double-click on an icon are important functions.
That is, in a system of this type, the operation mode for outputting absolute coordinates is essential. It is important to simultaneously realize this operation and the above-described relative operation.
Various arrangements are disclosed as methods of switching the operation mode. For example, in a method disclosed in Japanese Patent Laid-Open No. 4-299724, the display area is divided into an area where absolute coordinates can be input and an area where relative coordinates can be input. In addition, in methods disclosed in Japanese Patent Laid-Open Nos. 5-298014 and 10-333817, a relative/absolute coordinate switching means is used, or the operation is automatically switched in accordance with the application.
There is also disclosed a method of setting an offset value with respect to absolute coordinates, as disclosed in Japanese Patent Laid-Open No. 10-149253, or a method of processing coordinates in accordance with the moving speed of the pointing tool.
The method of dividing the area and the method of switching the operation mode in accordance with the application presume coordinate detection in the display area and disclose how to process detected coordinates. For example, when absolute point indication is to be executed in the area where relative coordinates can be detected, the set area must be set again, and the area containing the desired point position must be set as the area for absolute coordinate detection. Some setting is required even in the method of switching the operation on the basis of the application. The operation is very cumbersome.
In the arrangement having the switching means or the method of setting an offset amount by a specific operation, the specific operation such as switching occurs in accordance with the application purpose. Such an arrangement is not sufficiently advantageous from the viewpoint of operability. In the method of processing coordinates on the basis of the moving speed of the pointing tool, long-distance movement of a cursor can be realized by a small operation at hand. However, it is very difficult to input a character or draw a graphic pattern.
When a large input/output integrated system of this type, and briefings assuming many participants or the age of networking are taken into consideration, it is necessary not only to cause the operator to control an external device such as a personal computer by “directly touching the screens”, as described above. It is also preferable that, e.g., a participant at a conference, who is listening to the presentation while looking at the screen, can operate the screen or obtain information from the network, as needed, even at a “position separated from the screen” to ask a question or disclose evidential materials for a refutation.
In the conventional coordinate input apparatuses represented by apparatuses of a pressure sensitive type or electromagnetic type, the area where coordinates can be input (detected) is smaller than the size of the entire coordinate input apparatus. Hence, when a coordinate input apparatus is placed on a display apparatus such as a liquid crystal display, a range including the display area of the display apparatus and a numerical value that considers a tolerance in attaching the coordinate input apparatus to the display apparatus is generally set as the coordinate input effective area. The size of the display area is set to almost equal to that of the coordinate input effective area.
In other words, when specifications that allow detection outside the display apparatus are satisfied, the size of the coordinate input apparatus increases accordingly. The size of the entire apparatus becomes very large relative to the size of the display area.